To Next Page

To Previous Page

RM0440 Rev 4 507/2126

RM0440 Filter math accelerator (FMAC)

513

18.4.3 FMAC Y buffer configuration register (FMAC_YBUFCFG)

Address offset: 0x08

Reset value: 0x0000 0000

This register can only be modified if START = 0 in the FMAC_PARAM register.

Bits 31:16 Reserved, must be kept at reset value.

Bits 15:8 X2_BUF_SIZE[7:0]: Size of X2 buffer in 16-bit words

This bitfield can not be modified when a function is ongoing (START = 1).

Bits 7:0 X2_BASE[7:0]: Base address of X2 buffer

The X2 buffer base address can be modified while START=1, for example to change

coefficient values. The filter should be stalled when doing this, since changing the

coefficients while a calculation is ongoing affects the result.

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16

Res. Res. Res. Res. Res. Res. EMPTY_WM[1:0] Res. Res. Res. Res. Res. Res. Res. Res.

rw rw

1514131211109 8 765432 1 0

Y_BUF_SIZE[7:0] Y_BASE[7:0]

rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw

Bits 31:26 Reserved, must be kept at reset value.

Bits 25:24 EMPTY_WM[1:0]: Watermark for buffer empty flag

Defines the threshold for setting the Y buffer empty flag when operating in circular mode.

The flag is set if the number of unread values in the buffer is less than 2

EMPTY_WM

0: Threshold = 1

1: Threshold = 2

2: Threshold = 4

3: Threshold = 8

Setting a threshold greater than 1 allows several data to be transferred from the buffer under

one interrupt.

Threshold should be set to 1 if DMA read requests are enabled (DMAREN = 1 in FMAC_CR

Bits 23:16 Reserved, must be kept at reset value.

Bits 15:8 Y_BUF_SIZE[7:0]: Size of Y buffer in 16-bit words

For FIR filters, the minimum buffer size is 1 (+ the watermark threshold). For IIR filters the

minimum buffer size is the number of feedback taps (+ the watermark threshold).

Bits 7:0 Y_BASE[7:0]: Base address of Y buffer

ST STM32G473 User Manual

Questions and Answers: